Crude Oil, Fuels, and Organic Chemistry Flashcards
What is organic chemistry
The chemistry of carbon-based compounds
What do plastics use as a raw material
Crude oil
What is crude oil made of
Hydrocarbons
What is the method for separating out different types of crude oil
Frational distillation
Describe fractional distillation
- The oil is heated causing it to boil and turn into a gaseous mixture
- As the oil cools, the chemicals with lower boiling points will be the first to condense
- At various points the condensing liquid is extracted from the column
- The larger the molecule is, the lower its boiling point will be
How pure are the fractions from fractional distillation
Not at all - they’re a mixture of alkanes with broadly similar boiling points
Why do larger hydrocarbons have lower boiling points?
Because it takes a lot more energy to break all of the separate bonds
What is the second effect of long hydrocarbons
They’re more viscous (thick)
Give some examples of uses of hydrocarbons
Petrol, diesel, paraffin, methane, lubricating oi
What has to happen to a fuel for it to burn
It has to vaporise, as it is the vapour that burns, and to do this it is useful to have a low viscocity
What is a combustion reaction
A chemical reaction where a substance reacts with oxygen to produce heat, light, and new products
Which substances can be used as fuel
Any substance which is combustible
What happens in combustion when not enough oxygen is around
Incomplete combustion, where carbon is formed, as well as carbon monoxide, carbon dioxide, and water
Why is it important to avoid incomplete combustion
Because it creates carbon monoxide, which is toxic and we cannot detect
What is the issue with burning sulfur
Acid rain
How do we calculate the energy released with fuels
Energy transferred (J) = mass of water heated (g) x 4.2 x temperature rise
Why are we interested in hydrogen as a fuel?
Because it only creates water when it burns
2H(2) + O(2) = 2H(2)O
What are the problems with using hydrogen fuel cells in cars
- It’s very flammable and can explode
- For storage it must be chilled, compressed, and kept in strong tanks (-250)
- Manufacturing hydrogen requires the burning of CO(2)
Why is hydrogen used as a rocket fuel
Because it’s light and very powerful, burning at over 3000 degrees
How can we remove oxygen, heat, and fuel from the fire triangle
Oxygen - fire blankets, closing doors, covering a pan with a wet towel (carbon dioxide sinks oxygen rises)
Heat - putting water on a fire
Removing fuel - prevention. making clothing flame resistant and managing forests
How can we make the larger fractions from fractional distillation more useful
By catalytic cracking
How does catalytic cracking work
Vapour containing the unwanted fractions is passed over a very hot catalyst surface and this breaks them up
Give an example of catalytic cracking
C(15) H(32) = 2C(2)H(4) + C(8)H(18)
What types of hydrocarbons are created by catalytic cracking
A mixture of alkenes and alkanes
What types of hydrocarbons are alkanes
Saturated ones
Which types of alkanes do we have to know
Methane CH(4) Ethane C(2)H(6) Propane C(3)H(8) Butane C(4)H(10)
What type of compounds are alkanes
Homologous ones (very similar)
What are alkenes
Unsaturated hydrocarbons with a double bond between two carbon atoms
What is the name of a reaction where another atom is added to an alkene
An addition reaction
What is the name for when hydrogen is added to an alkene
Hydrogenation
How is hydrogenation achieved
By heating the alkene under pressure in the presence of a metallic catalyst
What is the chemical test for alkenes
That they turn orange bromine water colourless
How do you name a complex alkane/alkene
- Find the longest chain of carbon atoms (not always a straight line). This will be the “first name”
- Add ane or ene
- Work out how to number the carbon atoms. Carbon no.1 should be at the end nearest to a substituent group
- The substituent groups should be named according to how many carbon atoms they have
- In front of the name goes a prefix to show how many group there are
Define isomers
Two compounds that have the same formular but a different structural formula
Define polymer
A substance which has a molecular structure built up chiefly or completely from a large number of similar units bonded together
Give an example of a plastic hydrocarbons can make
Polythene, polypropene, or PVC
What are the two types of plastics
Thermoplastics - soften when heated
Thermosets - resistant to heat
What are thermosets used for
Light fittings and pan handles
What are thermoplastics used in
Household containers
What are thermoplastics made of
Polymer chains that aren’t linked together so can slide on one and other
How are thermosets constructed
The polymer chains have strong cross linkages which hold the structure together
How are thermoset plastics made
In liquid form - once set they can’t be remelted
What are the molecules (such as ethene) used to construct polymers called
Monomers
What are the two types of polymers
- Addition polymers (made from only one type of monomer)
- Condensation polymers (two or more types of monomer)
How is polythene made
By joining ethene molecules, heating them under pressure
How many ethene molecules join together making polythene
Between 2000 and 20000
What is polythene used in
Carrier bags
What is polypropene used in
Dishwasher safe food containers and piping
What is PVC used in
Electrical insulation, clothing, pipes
What is PTFE used in
Non stick coating for cookware and irons
What is the general formula for alcohols
C(n)H(2n+1)OH
How are alcohols named
Like alkanes but with -ol at the end
Which alcohols do you have to know
Methanol Ethanol Propan - 1 - ol Propan - 2 - ol Butanol
What happens in alcohol isomers
The OH molecule is positioned differently
What type of alcohol is in alcoholic drinks
Ethanol
How does fermentation happen
Yeast produces ethanol from sugar (only in anearobic conditions)
What is the formula for fermentation
C(6)H(12)O(6) = 2CO(2) + 2C(2)H(5)OH
What is the fermentation reaction catalyzed by
Enzymes which are produced by the yeast
What conditions are needed for fermentation
- The temperature should be between 25 and 50 degrees
- The fermentation tank has to be kept sterile
- Oxygen must be kept out
- Carbon dioxide has to be able to escape or else pressure will build up
What is the use of bioethanol
As a fuel - usually ethanol is mixed with petrol
What are the positives of ethanol as a fuel
- It’s renewable
- It emits less carbon dioxide than petrol
- It produces less soot and carbon monoxide
What are the disadvantages of ethanol as a fuel
- Fossil fuels are used in the production of bioethanol
- Ethanol is less efficient than petrol
- Engines need modifications to process ethanol
- Lots of farmland is needed to produce ethanol
How is vinegar made
Using ethanol - ethanoic acid is found in vinegar
What family of acids does ethanoic acid come from
Carboxylic acids, containing the group -COOH
What kind of reaction is converting ethanol to ethanoic acid
An oxidation reaction caused by microorganisms in aerobic conditions
How can alcohols be detected
By reaction with potassium dichromate and sulfuric acid, which will turn green if alcohol is present
What bond do alcohols have
An -OH one
What bond do carboxylic acids have
Bonds between carbon and oxygen, and between oxygen and hydrogen (-COOH)
What technique can scientists use to see what bonds are in a substance
Infrared spectroscopy
How does infrared spectroscopy work
Substances are but in an infrared spectrometer and infrared light is shone through them - different chemical bonds absorb different wavelengths of light, which can be displayed as an infrared spectrum. The peaks and troughs of this identify certain bonds, so this pattern (fingerprint) is unique to a particular molecule
